The present invention relates to an all-purpose conduit for conveying harmful fumes or gases away from a work station. More specifically, the present invention relates to a conduit comprising a fitting between an aspirator and a flexible conduit portion, and wherein the fitting rotates about its own axis to permit both radial and angular movement of a conveying element about the same axis.
Various conduits of the above type are known. In one, a long flexible conduit is provided between the fitting and the conveying element, and houses an articulated mechanism enabling the conduit to bend substantially at the center line; and the mechanism comprises a pair of spiral tension springs also housed inside the conduit and acting between an articulated plate and two opposite points of the mechanism. A major drawback of this type of conduit is the rapid deterioration caused by particles of the fumes depositing on the mechanism and springs.
Another known conduit features two rigid conduit segments, one of which is connected to the fitting at the top by means of a first flexible conduit portion; a second flexible conduit portion is fitted between the two rigid segments; the articulated connections between the fitting and the rigid segment and between the two rigid segments are made by means of pairs of hinged forks; high-friction disks are inserted between the arms of the forks; and spiral tension springs are inserted between the fitting and an intermediate point on the outside of the conduit.
A major drawback of this type of conduit is the considerable force required to overcome the friction of the disks to move the conveying element. Moreover, the springs, being external, are subject to fouling, and are released when struck accidentally; and, being a safety hazard, both the springs and forks should be shielded, thus increasing the cost of the conduit.
It is an object of the present invention to provide a highly straightforward, reliable conduit for conveying harmful fumes or gases, designed to overcome the aforementioned drawbacks typically associated with known conduits.
According to the present invention, there is provided an all-purpose conduit for conveying harmful fumes or gases away from a work station, and comprising a fitting between an aspirator and a flexible conduit portion, said fitting rotating about its own axis; at least one conduit segment connected to said flexible conduit portion; an articulated mechanism for varying the angular position of said conduit segment with respect to said fitting; and balancing spring means; characterized in that said mechanism comprises a pair of bars connected to each other in the form of an articulated parallelogram and forming a substantially closed channel; said spring means comprising a spiral compression spring housed in said channel and so connected as to function variously according to the angular position of said conduit segment with respect to said fitting.